1. Field of the Invention
The present invention relates to an endoscope equipped with a branch channel communicated with a first opening portion of a main channel in an operation portion.
2. Description of the Related Art
A configuration in which a tubular main channel is provided inside an insertion portion or an operation portion of an endoscope is well-known, where the insertion portion is inserted into a subject and the operation portion is connected to a proximal end of the insertion portion in an insertion axis direction.
Note that examples of the main channel include a treatment instrument insertion channel through which a treatment instrument is supplied into the subject and a balloon water injection channel through which an ultrasound transmission medium is supplied to a balloon provided in an insertion portion of an ultrasound endoscope.
The main channel includes a first opening portion which opens in an operation portion, and the first opening portion is communicated with a first end portion of a tubular branch channel whose second end portion opens outside the operation portion.
The branch channel is intended to supply a treatment instrument, ultrasound transmission medium, or the like to a main channel from the operation portion and is connected to the main channel in the operation portion such that the first end portion will be communicated with the first opening portion of the main channel. Note that examples of the branch channel include a treatment instrument insertion pipe sleeve and a balloon pipe sleeve connected with a syringe used to inject the ultrasound transmission medium.
Also, Japanese Patent Application Laid-Open Publication No. 2010-207424 discloses a configuration in which D-cuts are made in an inner circumferential face of a branch channel mounting hole provided in an operation portion and an outer circumferential face of a branch channel fitted in the branch channel mounting hole, and with the D-cut in the outer circumferential face of the branch channel and the D-cut in the inner circumferential face of the branch channel mounting hole abutting against each other, the branch channel is screw-fastened, preventing rotation of the branch channel after the fastening.
Now, if a tilting force is applied to the branch channel during operation of the endoscope, a tilting force is applied to a fixing section of the branch channel as well.
Note that cases in which the tilting force of the branch channel is applied include a case in which when the insertion portion is twisted with respect to the operation portion or when part of a grip of the operation portion provided with the branch channel is configured to be rotatable together with the branch channel, the part of the grip is rotated.